Under relentless pressure, President Donald Trump on Monday named and condemned "repugnant" hate groups and declared that "racism is evil" in a far more forceful statement than he'd made earlier after deadly, race-fueled weekend clashes in Charlottesville, Virginia.

Trump's initial failure on Saturday to denounce the groups by name - instead he bemoaned violence on "many sides" - prompted criticism from fellow Republicans as well as Democrats. This time, the president described members of the KKK, neo-Nazis and white supremacists who take part in violence as "criminals and thugs" in a prepared statement he read during an unscheduled address from the White House.

"Racism is evil," he said, singling out the hate groups as "repugnant to everything that we hold dear as Americans."

"Those who spread violence in the name of bigotry strike at the very core of America," he said.

In his remarks he also called for unity.

"We must love each other, show affection for each other and unite together in condemnation of hatred, bigotry and violence. We must rediscover the bonds of love and loyalty that bring us together as Americans," he said.

Trump also, for the first time, mentioned Heather Heyer by name, as he paid tribute to the woman killed when a car plowed into a group of anti-racist counter-protesters in Charlottesville.

The president left the White House room after his statement without acknowledging reporters' shouted questions.

Trump noted that the Justice Department has opened a civil rights investigation into the car crash that killed Heyer.

"To anyone who acted criminally in this weekend's racist violence, you will be held fully accountable. Justice will be delivered," he said.

His attorney general, Jeff Sessions, said earlier Monday that the violence "does meet the definition of domestic terrorism in our statute."

Sessions told ABC's "Good Morning America," ''You can be sure we will charge and advance the investigation toward the most serious charges that can be brought, because this is an unequivocally unacceptable and evil attack that cannot be accepted in America."

Trump gave his statement after meeting with Sessions and FBI Director Christopher Wray.

In the hours after the incident on Saturday, Trump addressed the violence in broad strokes, saying that he condemns "in the strongest possible terms this egregious display of hatred, bigotry and violence on many sides, on many sides."

That was met with swift bipartisan criticism.

Virginia Gov. Terry McAuliffe, a Democrat, said he spoke to Trump in the hours after the clashes and twice told the president "we have to stop this hateful speech, this rhetoric." He said he urged Trump "to come out stronger" against the actions of white supremacists.

Republicans joined Democrats in criticizing the president for not specifically calling out white nationalists. Sen. Cory Gardner of Colorado said Sunday on NBC, "This isn't a time for innuendo or to allow room to be read between the lines. This is a time to lay blame."

The White House scrambled to stem the tide of criticism, dispatching aides to the Sunday talk shows and sending out a statement that more forcefully denounced the hate groups.

But the White House did not attach a name to the statement. Usually, a statement would be signed by the press secretary or another staffer; not putting a name to one eliminates an individual's responsibility and often undercuts the significance.

White nationalists had assembled in Charlottesville to vent their frustration against the city's plans to take down a statue of Confederal Gen. Robert E. Lee. Counter-protesters massed in opposition.

Alt-right leader Richard Spencer and former Ku Klux Klan leader David Duke attended the demonstrations. Duke told reporters that the white nationalists were working to "fulfill the promises of Donald Trump."

Trump's initial comments drew praise from the neo-Nazi website Daily Stormer, which wrote: "Trump comments were good. He didn't attack us. He just said the nation should come together. Nothing specific against us. ... No condemnation at all." The website had been promoting the Charlottesville demonstration as part of its "Summer of Hate" edition.

Trump, as a presidential candidate, frequently came under scrutiny for being slow to offer his condemnation of white supremacists. His strongest denunciations of the movement have not come voluntarily, only when asked, and he occasionally has trafficked in retweets of racist social media posts during his campaign. His chief strategist, Steve Bannon, once declared that his former news site, Breitbart, was "the platform for the alt-right."

Early Monday, the CEO of the nation's third largest pharmaceutical company said he was resigning from the President's American Manufacturing Council, citing "a responsibility to take a stand against intolerance and extremism."

Trump lashed back almost immediately at Merck CEO Kenneth Frazier on Twitter, saying Frazier "will have more time to LOWER RIPOFF DRUG PRICES!"